JP2008051967A - Resist composition for liquid immersion lithography and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist composition for liquid immersion lithography having good lithography characteristics and also having hydrophobicity suitable for liquid immersion lithography, and a resist pattern forming method. <P>SOLUTION: The resist composition for liquid immersion lithography comprises a base material component (A) which undergoes a change in the alkali solubility under the action of an acid and which does not have a constitutional unit (c1) represented by formula (c1-1) [wherein R<SP>23</SP>is an alicyclic group having a structure (I) represented by general formula (I-1)], an acid generator component (B) which generates an acid upon exposure to light, and a fluorine-containing resin component (C) having the constitutional unit (c1). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resist composition for immersion exposure and a method for forming a resist pattern, which are used in liquid immersion lithography.

In lithography technology, for example, a resist film made of a resist material is formed on a substrate, and the resist film is selectively exposed to radiation such as light or an electron beam through a mask on which a predetermined pattern is formed. And a development process is performed to form a resist pattern having a predetermined shape on the resist film.
Along with the miniaturization of semiconductor elements, the wavelength of an exposure light source has been shortened and the projection lens has a high numerical aperture (high NA). A machine has been developed. Along with the shortening of the wavelength of the exposure light source, the resist material is required to be improved in lithography characteristics such as sensitivity to the exposure light source and resolution capable of reproducing a pattern with a fine dimension. As a resist material satisfying such requirements, a chemically amplified resist containing a base resin whose alkali solubility is changed by the action of an acid and an acid generator that generates an acid upon exposure is used.
Currently, as a base resin for a chemically amplified resist used in ArF excimer laser lithography and the like, a resin having a structural unit derived from a (meth) acrylate ester in the main chain because of its excellent transparency near 193 nm ( Acrylic resin) is generally used. Here, “(meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. “(Meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position. “(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.

As one of the methods for further improving the resolution, exposure (immersion exposure) is performed by interposing a liquid (immersion medium) having a higher refractive index than air between the objective lens of the exposure machine and the sample. A so-called immersion lithography (hereinafter referred to as “immersion exposure”) is known (for example, see Non-Patent Document 1).
According to immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the depth of focus can be reduced. It is said that there is no decline. Moreover, immersion exposure can be performed using an existing exposure apparatus. Therefore, immersion exposure is expected to be able to form a resist pattern with low cost, high resolution, and excellent depth of focus, and in the manufacture of semiconductor devices that require a large capital investment. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Immersion exposure is effective in forming all pattern shapes, and can be combined with super-resolution techniques such as the phase shift method and the modified illumination method that are currently being studied. Currently, as an immersion exposure technique, a technique mainly using an ArF excimer laser as a light source is being actively researched. Currently, water is mainly studied as an immersion medium.

In recent years, with respect to fluorine-containing compounds, their water repellency, transparency and other characteristics have attracted attention, and research and development in various fields has been actively conducted. For example, in the field of resist materials, acid instability such as a methoxymethyl group, tert-butyl group, tert-butyloxycarbonyl group, etc. is added to a fluorine-containing polymer compound for use as a base resin of a positive chemically amplified resist. Introducing groups. However, when such a fluorine-based polymer compound is used as a base resin of a positive resist composition, there are disadvantages such as generation of a large amount of outgas after exposure and insufficient resistance to dry etching gas (etching resistance).
Recently, a fluorine-containing polymer compound having an acid labile group containing a cyclic hydrocarbon group has been reported as a fluorine-containing polymer compound having excellent etching resistance (see, for example, Non-Patent Document 2).
Proceedings of SPIE, 5754, 119-128 (2005). Proceedings of SPIE, 4690, 76-83 (2002).

In immersion exposure, in addition to normal lithography characteristics (sensitivity, resolution, etching resistance, etc.), a resist material having characteristics corresponding to the immersion exposure technique is required. As a specific example, when the immersion medium is water and the immersion exposure is performed using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium is a lens. Water tracking is required to follow the movement of the water. If the water followability is low, the exposure speed is lowered, and there is a concern that the productivity is affected. This water followability is considered to be improved by increasing the hydrophobicity of the resist film (hydrophobizing). On the other hand, even if the resist film is simply hydrophobized, there is an adverse effect on the lithography properties. There is a tendency that the property and sensitivity decrease, the scum generation amount increases, and the like.
Thus, in immersion exposure, the development of materials having moderate hydrophobicity becomes an important issue. However, there are currently few known materials that satisfy both lithography characteristics and characteristics required for immersion exposure.
The present invention has been made in view of the above circumstances, and provides a resist composition for immersion exposure and a method for forming a resist pattern, which have good lithography characteristics and have hydrophobicity suitable for immersion exposure. The purpose is to do.

  The first aspect of the present invention that solves the above problem is a substrate that has alkali solubility changed by the action of an acid and does not have a structural unit (c1) represented by the following general formula (c1-1). A resist for immersion exposure comprising a component (A), an acid generator component (B) that generates acid upon exposure, and a fluororesin component (C) having the structural unit (c1). It is a composition.

［式（ｃ１−１）中、Ｒは水素原子、低級アルキル基、ハロゲン原子またはハロゲン化低級アルキル基であり、Ｒ^２１およびＲ^２２はそれぞれ独立して水素原子または低級アルキル基であり、ａは０〜３の整数であり、Ｒ^２３は、下記一般式（Ｉ−１）で表される構造（Ｉ）を有する脂肪族環式基である。］

[In the formula (c1-1), R is a hydrogen atom, a lower alkyl group, a halogen atom or a halogenated lower alkyl group, R ²¹ and R ²² are each independently a hydrogen atom or a lower alkyl group, and a is R is an integer of 0 to 3, and R ²³ is an aliphatic cyclic group having the structure (I) represented by the following general formula (I-1). ]

［式（Ｉ−１）中、Ｒ^２４およびＲ^２５はそれぞれ独立してフッ素原子またはフッ素化アルキル基であり、Ｘ^２１およびＸ^２２はそれぞれ当該構造（Ｉ）を有する脂肪族環式基の環骨格を構成する炭素原子である。］

[In Formula (I-1), R ²⁴ and R ²⁵ each independently represent a fluorine atom or a fluorinated alkyl group, and X ²¹ and X ²² each represent a ring of an aliphatic cyclic group having the structure (I). It is a carbon atom constituting the skeleton. ]

  According to a second aspect of the present invention, there is provided a step of forming a resist film on a support using the resist composition for immersion exposure according to the first aspect, a step of immersion exposure of the resist film, and the resist film. A resist pattern forming method including a step of forming a resist pattern by development.

In the present specification and claims, unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
A “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
The “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups unless otherwise specified.
“Structural unit” means a monomer unit (monomer unit) constituting a resin (polymer).
“Exposure” is a concept that includes radiation exposure in general.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resist composition for immersion exposure and a method for forming a resist pattern that have good lithography properties and have hydrophobicity suitable for immersion exposure.

≪Resist composition for immersion exposure≫
The resist composition for immersion exposure according to the present invention has a base material component (A) whose alkali solubility is changed by the action of an acid and does not have the structural unit (c1) represented by the general formula (c1-1). ) (Hereinafter referred to as component (A)), an acid generator component (B) (hereinafter referred to as component (B)) that generates an acid upon exposure, and the general formula (c1-1). A fluorine-containing resin component (C) having a structural unit (c1) (hereinafter referred to as “component (C)”).

<(A) component>
The component (A) is not particularly limited as long as it does not contain the structural unit (c1), and is a base component for a chemically amplified resist composition, for example, a resist composition for ArF excimer laser, for KrF excimer laser ( It may be arbitrarily selected and used from among many proposed substrate components such as resist compositions (preferably for ArF excimer laser). The structural unit (c1) will be described in the section of the component (C) described later.
Here, “base material component” means an organic compound having film-forming ability.
Preferable base material components include organic compounds having a molecular weight of 500 or more. When the molecular weight of the organic compound is 500 or more, the film forming ability is improved and a nano-level pattern is easily formed.
The organic compound having a molecular weight of 500 or more is roughly classified into a low molecular weight organic compound having a molecular weight of 500 to less than 2000 (hereinafter referred to as a low molecular compound) and a high molecular weight resin having a molecular weight of 2000 or more (polymer). Is done. As the low molecular weight compound, a non-polymer is usually used. In the case of a resin (polymer), a polystyrene-reduced weight average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” refers to a resin having a molecular weight of 2000 or more.
The component (A) may be a low molecular compound whose alkali solubility is changed by the action of an acid, a resin whose alkali solubility is changed by the action of an acid, or a mixture thereof. Good.

The resist composition for immersion exposure according to the present invention may be a negative resist composition or a positive resist composition.
When the resist composition for immersion exposure of the present invention is a negative resist composition, as the component (A), a base material component whose alkali solubility is lowered by the action of an acid is used. As such a base material component, an alkali-soluble resin is usually used.
In the case of the negative type, the resist composition further contains a crosslinking agent component. In such a resist composition, when an acid is generated from the component (B) by exposure during resist pattern formation, the acid acts to cause crosslinking between the component (A) and the cross-linking agent, so that the alkali-soluble resin becomes alkali-insoluble. And change. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the resist composition on the substrate is selectively exposed, the exposed portion turns into alkali-insoluble while the unexposed portion remains alkali-soluble. Since it does not change, a resist pattern can be formed by alkali development.
As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is a good resist with little swelling. A pattern can be formed, which is preferable. Note that α- (hydroxyalkyl) acrylic acid includes acrylic acid in which a hydrogen atom is bonded to the α-position carbon atom to which the carboxy group is bonded, and a hydroxyalkyl group (preferably having 1 carbon atom) in the α-position carbon atom. One or both of [alpha] -hydroxyalkylacrylic acids to which (5) hydroxyalkyl groups) are attached.
As the crosslinking agent component, for example, it is usually preferable to use an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group because a good resist pattern with less swelling can be formed. The blending amount of the crosslinking agent component is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

  When the resist composition for immersion exposure of the present invention is a positive resist composition, the component (A) is a base material component having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid. Is used. The resist composition containing such a base component is insoluble in alkali before exposure, and when an acid is generated from component (B) by exposure during resist pattern formation, the acid dissociable, dissolution inhibiting group is dissociated by the action of the acid. , (A) component changes to alkali-soluble. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the positive resist composition on the substrate is selectively exposed, the exposed portion turns into alkali-soluble while the unexposed portion is alkali-insoluble. Thus, the resist pattern can be formed by alkali development.

In the resist composition for immersion exposure according to the present invention, the component (A) is preferably a base material component whose alkali solubility is increased by the action of an acid because it is excellent in the effects of the present invention. That is, the resist composition for immersion exposure according to the present invention is preferably a positive resist composition.
The substrate component may be a resin (A1) whose alkali solubility is increased by the action of an acid (hereinafter sometimes referred to as the component (A1)), and a low molecular weight compound whose alkali solubility is increased by the action of an acid. (A2) (hereinafter also referred to as component (A2)) may be used.
In consideration of miscibility with component (C), availability, etc., component (A) is preferably component (A1).

[(A1) component]
The component (A1) is not particularly limited, and any of those conventionally proposed as a base resin for a positive chemically amplified resist can be used. Examples of such a base resin include alkali-soluble compounds. Examples include a resin in which a part or all of the alkali-soluble group in a resin having a group (hydroxyl group, carboxy group, etc.) is protected with an acid dissociable, dissolution inhibiting group. Examples of the resin having an alkali-soluble group include a novolak resin, a resin having a structural unit derived from hydroxystyrene (polyhydroxystyrene, hydroxystyrene-styrene copolymer, etc.), and a structural unit derived from an acrylate ester. And a resin having a structural unit derived from a cycloolefin.
In the present invention, the component (A1) is preferably a resin having a structural unit derived from an acrylate ester. Such a resin is particularly highly transparent to an ArF excimer laser, and can be suitably used in lithography using an ArF excimer laser.
In the component (A1), the proportion of the structural unit derived from the acrylate ester is preferably 20 mol% or more, more preferably 50 mol% or more based on the total of all the structural units constituting the component (A1). More preferably, 80 mol% or more is more preferable, and 100 mol% may be sufficient.

Here, in the present specification and claims, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent include a halogen atom, a lower alkyl group, and a halogenated lower alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The α-position (α-position carbon atom) of a structural unit derived from an acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, more preferably a hydrogen atom or a lower alkyl group. Preferably, it is most preferably a hydrogen atom or a methyl group in view of industrial availability.

"Structural unit (a1)"
In the present invention, the component (A1) preferably has a structural unit (a1) derived from an acrylate ester having an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire resin (A1) insoluble in alkali before dissociation, and changes the entire resin (A1) to alkali soluble after dissociation. If it is a thing, the thing proposed so far as an acid dissociable, dissolution inhibiting group of the base resin for chemically amplified resists can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group in (meth) acrylic acid or the like; an acetal-type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group is widely known. .

Here, the “tertiary alkyl ester” is an ester formed by replacing a hydrogen atom of a carboxy group with a chain or cyclic alkyl group, and the carbonyloxy group (—C (O)). A structure in which the tertiary carbon atom of the chain or cyclic alkyl group is bonded to the terminal oxygen atom of -O-). In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The chain or cyclic alkyl group may have a substituent.
Hereinafter, a group that is acid dissociable by constituting a carboxy group and a tertiary alkyl ester is referred to as a “tertiary alkyl ester type acid dissociable, dissolution inhibiting group” for convenience.
Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.

Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
“Aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-amyl group, and a tert-heptyl group. .

The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Specific examples of the aliphatic cyclic group include, for example, a monocycloalkane, a bicycloalkane, a tricycloalkane, which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group, Examples thereof include a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group. Specifically, 2-methyl-2 -Adamantyl group, 2-ethyl-2-adamantyl group, etc. are mentioned. Alternatively, in a structural unit represented by the following general formula (a1 ″), an aliphatic cyclic group such as an adamantyl group, such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—); And a group having a branched alkylene group having a tertiary carbon atom bonded thereto.

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ^１５、Ｒ^１６はアルキル基（直鎖、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である）を示す。］

[Wherein, R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹⁵ and R ¹⁶ may be alkyl groups (both linear and branched, preferably 1 to 1 carbon atoms) 5). ]

  In the formula (a1 ″), the halogen atom, lower alkyl group or halogenated lower alkyl group represented by R is the halogen atom, lower alkyl group or halogenated lower group mentioned as the substituent at the α-position in the description of the acrylic ester. The same thing as an alkyl group is mentioned.

The “acetal-type acid dissociable, dissolution inhibiting group” is generally bonded to an oxygen atom by substituting a hydrogen atom at the terminal of an alkali-soluble group such as a carboxy group or a hydroxyl group. When an acid is generated by exposure, the acid acts to break the bond between the acetal acid dissociable, dissolution inhibiting group and the oxygen atom to which the acetal acid dissociable, dissolution inhibiting group is bonded.
Examples of the acetal type acid dissociable, dissolution inhibiting group include a group represented by the following general formula (p1).

［式中、Ｒ^１’，Ｒ^２’はそれぞれ独立して水素原子または低級アルキル基を表し、ｎは０〜３の整数を表し、Ｙは低級アルキル基または脂肪族環式基を表す。］

[Wherein, R ^{1 ′} and R ^{2 ′} each independently represent a hydrogen atom or a lower alkyl group, n represents an integer of 0 to 3, and Y represents a lower alkyl group or an aliphatic cyclic group. ]

In the above formula, n is preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.
Examples of the lower alkyl group for R ^{1 ′} and R ^{2 ′} include the same lower alkyl groups as those described above for R. A methyl group or an ethyl group is preferable, and a methyl group is most preferable.
In the present invention, at least one of R ^{1 ′} and R ^{2 ′} is preferably a hydrogen atom. That is, the acid dissociable, dissolution inhibiting group (p1) is preferably a group represented by the following general formula (p1-1).

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

[Wherein, R ^{1 ′} , n and Y are the same as described above. ]

Examples of the lower alkyl group for Y include the same lower alkyl groups as those described above for R.
The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups conventionally proposed in a number of ArF resists and the like. For example, the above “aliphatic ring” Examples thereof are the same as those in the formula group.

  Examples of the acetal type acid dissociable, dissolution inhibiting group also include a group represented by the following general formula (p2).

［式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐鎖状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐鎖状または環状のアルキル基である。または、Ｒ^１７およびＲ^１９がそれぞれ独立に直鎖状または分岐鎖状のアルキレン基であって、Ｒ^１７の末端とＲ^１９の末端とが結合して環を形成していてもよい。］

[Wherein, R ¹⁷ and R ¹⁸ each independently represent a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ represents a linear, branched or cyclic alkyl group. Alternatively, R ¹⁷ and R ¹⁹ may be each independently a linear or branched alkylene group, and the end of R ^{17 and} the end of R ¹⁹ may be bonded to form a ring. ]

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include groups excluding hydrogen atoms. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
In the above formula, R ¹⁷ and R ¹⁹ are each independently a linear or branched alkylene group (preferably an alkylene group having 1 to 5 carbon atoms), and the end of R ^{19 and} the end of R ¹⁷ And may be combined.
In this case, a cyclic group is formed by R ¹⁷ , R ¹⁹ , the oxygen atom to which R ¹⁹ is bonded, and the carbon atom to which the oxygen atom and R ¹⁷ are bonded. The cyclic group is preferably a 4-7 membered ring, and more preferably a 4-6 membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

  As the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-0-1) and structural units represented by the following general formula (a1-0-2): Is preferably used.

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; and X ¹ represents an acid dissociable, dissolution inhibiting group. ]

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an alkylene group or an aliphatic cyclic group. ]

In the general formula (a1-0-1), the halogen atom, lower alkyl group or halogenated lower alkyl group of R is a halogen atom, lower alkyl group or halogenated lower group which may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include the above-described tertiary alkyl ester type acid dissociable, dissolution inhibiting group and acetal type acid dissociable, dissolution inhibiting group. A tertiary alkyl ester type acid dissociable, dissolution inhibiting group is preferred.

In general formula (a1-0-2), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group, and the aliphatic cyclic group is the above except that a group in which two or more hydrogen atoms are removed is used. The thing similar to description of an "aliphatic cyclic group" can be used.

  More specifically, examples of the structural unit (a1) include structural units represented by the following general formulas (a1-1) to (a1-4).

［上記式中、Ｘ’は第３級アルキルエステル型酸解離性溶解抑制基を表し、Ｙは炭素数１〜５の低級アルキル基、または脂肪族環式基を表し；ｎは０〜３の整数を表し；ｍは０または１を表し；Ｒは前記と同じであり、Ｒ^１’、Ｒ^２’はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基を表す。］

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; M represents 0 or 1; R is the same as defined above; R ¹ ′ and R ² ′ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. ]

At least one of R ¹ ′ and R ² ′ is preferably a hydrogen atom, more preferably a hydrogen atom. n is preferably 0 or 1.

X ′ is the same as the tertiary alkyl ester type acid dissociable, dissolution inhibiting group exemplified in X ¹ above.
Examples of the aliphatic cyclic group for Y include the same groups as those exemplified above in the description of “aliphatic cyclic group”.

  Specific examples of the structural units represented by the general formulas (a1-1) to (a1-4) are shown below.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Among these, the structural unit represented by the general formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) or (a1-1-35) to (a1- It is more preferable to use at least one selected from structural units represented by 1-41).
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formulas (a1-1-1) to (a1-1-4) The following general formula (a1-1-02) including the structural units of formulas (a1-1-35) to (a1-1-41) is also preferable.

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹¹ represents a lower alkyl group.)

（式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１２は低級アルキル基を示す。ｈは１〜３の整数を表す）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ¹² represents a lower alkyl group, and h represents an integer of 1 to 3).

In general formula (a1-1-01), R is the same as defined above. The lower alkyl group for R ^{11 is the same as} the lower alkyl group for R, and is preferably a methyl group or an ethyl group.

In general formula (a1-1-02), R is the same as defined above. The lower alkyl group for R ^{12 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group. h is preferably 1 or 2, and most preferably 2.

  In the component (A1), the proportion of the structural unit (a1) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, based on all the structural units constituting the copolymer (A1). More preferred is mol%. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
In addition to the structural unit (a1), the component (A1) preferably further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring. When only the lactone ring is present, it is called a monocyclic group. When it has another ring structure, it is called a polycyclic group regardless of the structure.
When the component (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in raising.

As the structural unit (a2), any unit can be used without any particular limitation.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring.

  More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数であり、Ａは炭素数１〜５のアルキレン基または酸素原子である。］

[Wherein, R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is 0 or 1 is an integer, and A is an alkylene group having 1 to 5 carbon atoms or an oxygen atom. ]

R in the general formulas (a2-1) to (a2-5) is the same as R in the structural unit (a1).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
Specific examples of the alkylene group having 1 to 5 carbon atoms of A include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

  Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-5), and at least one selected from general formulas (a2-1) to (a2-3). It is preferable to use more than one species. Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

In the component (A1), as the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the component (A1) is preferably 5 to 60 mol%, more preferably 10 to 60 mol%, with respect to the total of all structural units constituting the component (A1). 55 mol% is more preferable. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3)
The component (A1) is derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural unit (a1) and the structural unit (a2). It is preferable to have a structural unit (a3). By having the structural unit (a3), the hydrophilicity of the component (A1) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). . As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

  The structural unit (a3) is derived from a hydroxyethyl ester of acrylic acid when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms. When the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), (a3-3) The structural unit represented by is mentioned as a preferable thing.

（式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数であり、ｔ’は１〜３の整数であり、ｌは１〜５の整数であり、ｓは１〜３の整数である。）

(Wherein R is the same as above, j is an integer of 1 to 3, k is an integer of 1 to 3, t ′ is an integer of 1 to 3, and l is an integer of 1 to 5) And s is an integer of 1 to 3.)

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group is bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.
j is preferably 1, and a hydroxyl group bonded to the 3-position of the adamantyl group is particularly preferred.

  In formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5th or 6th position of the norbornyl group.

  In formula (a3-3), t ′ is preferably 1. l is preferably 1. s is preferably 1. These preferably have a 2-norbornyl group or a 3-norbornyl group bonded to the terminal of the carboxy group of acrylic acid. The fluorinated alkyl alcohol is preferably bonded to the 5th or 6th position of the norbornyl group.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
In the component (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, based on all structural units constituting the component (A1). More preferred is ˜25 mol%.

・ Structural unit (a4)
The copolymer (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1) to (a3) described above. For ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser) A number of conventionally known resins can be used for resist resins such as
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used for the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

(In the formula, R is as defined above.)

  When the structural unit (a4) is contained in the component (A1), the structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 10% of the total of all the structural units constituting the component (A1). It is preferable to contain 20 mol%.

  In the present invention, the component (A1) is preferably a copolymer having the structural units (a1), (a2) and (a3). Examples of such a copolymer include a copolymer composed of the structural units (a1), (a2) and (a3), and a copolymer composed of the structural units (a1), (a2), (a3) and (a4). A polymer etc. can be illustrated.

  As the component (A1), a copolymer having three structural units represented by the following general formula (A-11) is particularly preferable.

In formula (A1-11), R is the same as defined above, and R ¹⁰ represents a lower alkyl group.
The lower alkyl group for R ^{10 is the same as} the lower alkyl group for R, and is preferably a methyl group or an ethyl group, and most preferably a methyl group.

The component (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
Further, for the component (A1), in the polymerization, a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination, so that the terminal A —C (CF ₃ ) ₂ —OH group may be introduced into the. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw) of the component (A1) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and most preferably 5000 to 20000. preferable. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and when it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
The dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and still more preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

[(A2) component]
The component (A2) is preferably a low molecular compound having a molecular weight of 500 or more and 2000 or less and having an acid dissociable, dissolution inhibiting group and a hydrophilic group as exemplified in the description of the component (A1). Specific examples include those in which a part of the hydrogen atoms of the hydroxyl group of the compound having a plurality of phenol skeletons is substituted with the acid dissociable, dissolution inhibiting group.
The component (A2) is, for example, a part of the hydrogen atom of the hydroxyl group of a low molecular weight phenol compound known as a sensitizer or heat resistance improver for non-chemically amplified g-line or i-line resists. Those substituted with a dissolution inhibiting group are preferred, and any of them can be used arbitrarily.
Examples of such low molecular weight phenol compounds include bis (4-hydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl). ) Propane, 2- (2,3,4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-) 3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3, 4-dihydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphene Nylmethane, bis (4-hydroxy-3-methylphenyl) -3,4-dihydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl- 4-hydroxy-6-methylphenyl) -3,4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, Examples include 2, 3, 4 nuclei of formalin condensates of phenols such as phenol, m-cresol, p-cresol or xylenol. Of course, it is not limited to these.
The acid dissociable, dissolution inhibiting group is not particularly limited, and examples thereof include those described above.

As the component (A), one type may be used alone, or two or more types may be used in combination.
In the present invention, the component (A) preferably has no fluorine atom. When the component (A) does not contain a fluorine atom, the effects of the present invention are improved, and in particular, the lithography properties are improved.
The content of the component (A) in the resist composition for immersion exposure according to the present invention may be adjusted according to the resist film thickness to be formed.

<(B) component>
The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Examples of the onium salt acid generator include an acid generator represented by the following general formula (b-0).

［式中、Ｒ^５１は、直鎖、分岐鎖若しくは環状のアルキル基、または直鎖、分岐鎖若しくは環状のフッ素化アルキル基を表し；Ｒ^５２は、水素原子、水酸基、ハロゲン原子、直鎖若しくは分岐鎖状のアルキル基、直鎖若しくは分岐鎖状のハロゲン化アルキル基、または直鎖若しくは分岐鎖状のアルコキシ基であり；Ｒ^５３は置換基を有していてもよいアリール基であり；ｕ”は１〜３の整数である。］

[Wherein R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, linear or A branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group; R ⁵³ is an optionally substituted aryl group; u "Is an integer from 1 to 3.]

In General Formula (b-0), R ⁵¹ represents a linear, branched, or cyclic alkyl group, or a linear, branched, or cyclic fluorinated alkyl group.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of the number of substituted fluorine atoms to the total number of hydrogen atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly Those in which all hydrogen atoms are substituted with fluorine atoms are preferred because the strength of the acid is increased.
R ⁵¹ is most preferably a linear alkyl group or a fluorinated alkyl group.

R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, a linear or branched alkyl group, a linear or branched alkyl halide group, or a linear or branched alkoxy group.
In R ⁵² , examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and a fluorine atom is preferable.
In R ⁵² , the alkyl group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
In R ⁵² , the halogenated alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms. Examples of the alkyl group herein are the same as the “alkyl group” in R ⁵² . Examples of the halogen atom to be substituted include the same as those described above for the “halogen atom”. In the halogenated alkyl group, it is desirable that 50 to 100% of the total number of hydrogen atoms are substituted with halogen atoms, and it is more preferable that all are substituted.
In R ⁵² , the alkoxy group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
Among these, R ⁵² is preferably a hydrogen atom.

R ⁵³ is an aryl group which may have a substituent, and examples of the structure of the basic ring (matrix ring) excluding the substituent include a naphthyl group, a phenyl group, an anthracenyl group, and the like. From the viewpoint of absorption of exposure light such as ArF excimer laser, a phenyl group is desirable.
Examples of the substituent include a hydroxyl group and a lower alkyl group (straight or branched chain, preferably having 5 or less carbon atoms, particularly preferably a methyl group).
As the aryl group for R ^53, an aryl group having no substituent is more preferable.
u ″ is an integer of 1 to 3, preferably 2 or 3, and particularly preferably 3.

  Preferable examples of the acid generator represented by the general formula (b-0) include the following.

  Moreover, as an onium salt type acid generator other than the acid generator represented by general formula (b-0), the compound represented by the following general formula (b-1) or (b-2) is mentioned, for example. .

［式中、Ｒ^１”〜Ｒ^３”，Ｒ^５”〜Ｒ^６”は、それぞれ独立に、アリール基またはアルキル基を表し；Ｒ^４”は、直鎖、分岐または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[Wherein, R ¹ ″ to R ³ ″ and R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group; R ⁴ ″ represents a linear, branched or cyclic alkyl group or fluorinated group. Represents an alkyl group; at least one of R ¹ ″ to R ³ ″ represents an aryl group, and at least one of R ⁵ ″ to R ⁶ ″ represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. At least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all of R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
The alkoxy group that may be substituted with a hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may be substituted for the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are most preferably a phenyl group or a naphthyl group, respectively.

R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. It is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. It is preferable that all of R ⁵ ″ to R ⁶ ″ are aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
As the alkyl group for R ⁵ ″ to R ⁶ ″, the same as the alkyl groups for R ¹ ″ to R ³ ″ can be used.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.
"As ^{R 4} in the formula (b-1)" ^{R 4} in the In the formula (b-2) include the same as.

  Specific examples of the onium salt acid generators represented by the formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Sulfonate or its nonafluorobutane sulfonate, di (1-naphthyl) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate. In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

  In addition, in the general formula (b-1) or (b-2), an onium salt-based acid generator in which the anion moiety is replaced with an anion moiety represented by the following general formula (b-3) or (b-4). Can also be used (the cation moiety is the same as (b-1) or (b-2)).

［式中、Ｘ”は、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｙ”、Ｚ”は、それぞれ独立に、少なくとも１つの水素原子がフッ素原子で置換された炭素数１〜１０のアルキル基を表す。］

[Wherein X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; Y ″ and Z ″ each independently represent at least one hydrogen atom as a fluorine atom; Represents an alkyl group having 1 to 10 carbon atoms and substituted with

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Preferably it is C3.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably It is C1-C7, More preferably, it is C1-C3.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, the strength of the acid increases as the number of hydrogen atoms substituted with fluorine atoms increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Moreover, the sulfonium salt which has a cation part represented by the following general formula (b-5) or (b-6) can also be used as an onium salt type | system | group acid generator.

［式中、Ｒ^４１〜Ｒ^４６はそれぞれ独立してアルキル基、アセチル基、アルコキシ基、カルボキシ基、水酸基またはヒドロキシアルキル基であり、ｎ_１〜ｎ_５はそれぞれ独立して０〜３の整数であり、ｎ_６は０〜２の整数である。］

[Wherein, R ^{41 to} R ⁴⁶ each independently represents an alkyl group, an acetyl group, an alkoxy group, a carboxy group, a hydroxyl group or a hydroxyalkyl group, and n _{1 to} n ₅ each independently represents an integer of 0 to 3. There, _{n 6} is an integer of 0-2. ]

In R ^{41 to} R ⁴⁶ , the alkyl group is preferably a lower alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group, and a methyl group, an ethyl group, a propyl group, an isopropyl group, Particularly preferred is an n-butyl group or a tert-butyl group.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a linear or branched alkoxy group, and particularly preferably a methoxy group or an ethoxy group.
The hydroxyalkyl group is preferably a group in which one or more hydrogen atoms of the alkyl group are substituted with a hydroxy group, and examples thereof include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, and the like.
n ₁ is preferably 1 or 2, more preferably 1.
n ₂ and n ₃ are preferably each independently 0 or 1, more preferably 0.
n ₄ is preferably 1 or 2, and more preferably 1.
n ₅ is preferably 0 or 1, more preferably 0.
n ₆ is preferably 0 or 1, more preferably 1.

The anion part of the sulfonium salt having a cation part represented by the formula (b-5) or (b-6) is not particularly limited, and is the same as the anion part of the onium salt acid generators proposed so far. It may be a thing. Examples of the anion moiety include an anion moiety (R ⁵¹ —SO ₃ ⁻ ) of the onium salt acid generator represented by the general formula (b-0), the general formula (b-1), or (b-2). for onium salt-based acid generator represented _{^{by) (R 4 "-SO 3 -}} ) or the anion, and the like represented by the general formula (b-3) or (b-4).
Preferred specific examples of the sulfonium salt having a cation moiety represented by the formula (b-5) or (b-6) are given below.

  In this specification, the oxime sulfonate acid generator is a compound having at least one group represented by the following general formula (B-1), and has a property of generating an acid upon irradiation with radiation. is there. Such oxime sulfonate-based acid generators are frequently used for chemically amplified resist compositions, and can be arbitrarily selected and used.

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

(In formula (B-1), R ³¹ and R ³² each independently represents an organic group.)

The organic groups of R ³¹ and R ³² are groups containing carbon atoms, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms (fluorine atoms, chlorine atoms, etc.), etc.) You may have.
As the organic group for R ³¹ , a linear, branched, or cyclic alkyl group or aryl group is preferable. These alkyl groups and aryl groups may have a substituent. There is no restriction | limiting in particular as this substituent, For example, a fluorine atom, a C1-C6 linear, branched or cyclic alkyl group etc. are mentioned. Here, “having a substituent” means that part or all of the hydrogen atoms of the alkyl group or aryl group are substituted with a substituent.
As an alkyl group, C1-C20 is preferable, C1-C10 is more preferable, C1-C8 is more preferable, C1-C6 is especially preferable, and C1-C4 is the most preferable. As the alkyl group, a partially or completely halogenated alkyl group (hereinafter sometimes referred to as a halogenated alkyl group) is particularly preferable. The partially halogenated alkyl group means an alkyl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated alkyl group means that all of the hydrogen atoms are halogen atoms. Means an alkyl group substituted with Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.
The aryl group preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the aryl group, a partially or completely halogenated aryl group is particularly preferable. The partially halogenated aryl group means an aryl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated aryl group means that all of the hydrogen atoms are halogen atoms. Means an aryl group substituted with.
R ³¹ is particularly preferably an alkyl group having 1 to 4 carbon atoms or a fluorinated alkyl group having 1 to 4 carbon atoms which has no substituent.

As the organic group for R ³² , a linear, branched, or cyclic alkyl group, aryl group, or cyano group is preferable. As the alkyl group and aryl group for R ^32, the same alkyl groups and aryl groups as those described above for R ³¹ can be used.
R ³² is particularly preferably a cyano group, an alkyl group having 1 to 8 carbon atoms having no substituent, or a fluorinated alkyl group having 1 to 8 carbon atoms.

  More preferable examples of the oxime sulfonate-based acid generator include compounds represented by the following general formula (B-2) or (B-3).

［式（Ｂ−２）中、Ｒ^３３は、シアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３４はアリール基である。Ｒ^３５は置換基を有さないアルキル基またはハロゲン化アルキル基である。］

[In Formula (B-2), R ³³ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁴ is an aryl group. R ³⁵ represents an alkyl group having no substituent or a halogenated alkyl group. ]

［式（Ｂ−３）中、Ｒ^３６はシアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３７は２または３価の芳香族炭化水素基である。Ｒ^３８は置換基を有さないアルキル基またはハロゲン化アルキル基である。ｐ”は２または３である。］

[In Formula (B-3), R ³⁶ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁷ is a divalent or trivalent aromatic hydrocarbon group. ^R38 is an alkyl group having no substituent or a halogenated alkyl group. p ″ is 2 or 3.]

In the general formula (B-2), the alkyl group or halogenated alkyl group having no substituent of R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and carbon atoms. Numbers 1 to 6 are most preferable.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³³ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more, and still more preferably 90% or more.

As the aryl group of R ³⁴ , one hydrogen atom is removed from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthracyl group, or a phenanthryl group. And heteroaryl groups in which some of the carbon atoms constituting the ring of these groups are substituted with heteroatoms such as oxygen, sulfur, and nitrogen atoms. Among these, a fluorenyl group is preferable.
The aryl group of R ³⁴ may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or an alkoxy group. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group.

The alkyl group or halogenated alkyl group having no substituent for R ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group, and most preferably a partially fluorinated alkyl group.
The fluorinated alkyl group in R ³⁵ preferably has 50% or more of the hydrogen atom of the alkyl group, more preferably 70% or more, and even more preferably 90% or more fluorinated. This is preferable because the strength of the acid is increased. Most preferred is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

In the general formula (B-3), the alkyl group or halogenated alkyl group having no substituent for R ³⁶ is the same as the alkyl group or halogenated alkyl group having no substituent for R ^33. Is mentioned.
Examples of the divalent or trivalent aromatic hydrocarbon group for R ³⁷ include groups obtained by further removing one or two hydrogen atoms from the aryl group for R ³⁴ .
Examples of the alkyl group or halogenated alkyl group having no substituent of R ³⁸ include the same alkyl groups or halogenated alkyl groups having no substituent as R ³⁵ described above.
p ″ is preferably 2.

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

  Of the above exemplified compounds, the following four compounds are preferred.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Further, diazomethane acid generators disclosed in JP-A-11-035551, JP-A-11-035552, and JP-A-11-035573 can also be suitably used.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane and 1,4-bis (phenylsulfonyldiazo) disclosed in JP-A-11-322707. Methylsulfonyl) butane, 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane, 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane, 1,3 -Bis (cyclohexylsulfonyldiazomethylsulfonyl) propane, 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane, etc. Door can be.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, as the component (B), among the above, it is preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(C) component>
(C) A component has the structural unit (c1) represented by the following general formula (c1-1).

［式（ｃ１−１）中、Ｒは水素原子、低級アルキル基、ハロゲン原子またはハロゲン化低級アルキル基であり、Ｒ^２１およびＲ^２２はそれぞれ独立して水素原子または低級アルキル基であり、ａは０〜３の整数であり、Ｒ^２３は、下記一般式（Ｉ−１）で表される構造（Ｉ）を有する脂肪族環式基である。］

[In the formula (c1-1), R is a hydrogen atom, a lower alkyl group, a halogen atom or a halogenated lower alkyl group, R ²¹ and R ²² are each independently a hydrogen atom or a lower alkyl group, and a is R is an integer of 0 to 3, and R ²³ is an aliphatic cyclic group having the structure (I) represented by the following general formula (I-1). ]

［式（Ｉ−１）中、Ｒ^２４およびＲ^２５はそれぞれ独立してフッ素原子またはフッ素化アルキル基であり、Ｘ^２１およびＸ^２２はそれぞれ当該構造（Ｉ）を有する脂肪族環式基の環骨格を構成する炭素原子である。］

[In Formula (I-1), R ²⁴ and R ²⁵ each independently represent a fluorine atom or a fluorinated alkyl group, and X ²¹ and X ²² each represent a ring of an aliphatic cyclic group having the structure (I). It is a carbon atom constituting the skeleton. ]

In the formula (c1-1), as the lower alkyl group, halogen atom or halogenated lower alkyl group for R, R in the component (A), that is, the halogen atom or lower group listed as the substituent at the α-position of the acrylate ester, Examples are the same as the alkyl group or the halogenated lower alkyl group.
R is preferably a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorinated alkyl group, and is preferably a hydrogen atom or a methyl group in terms of industrial availability.
Specific examples of the lower alkyl group for R ²¹ and R ²² include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. And a lower linear or branched alkyl group is preferable, a methyl group or an ethyl group is preferable, and a methyl group is most preferable.
In the present ^invention, it is preferable that at least one of ^{R 21} and ^{R 22} is a hydrogen ^atom, and most preferably both of ^{R 21} and ^{R 22} are hydrogen atoms.
a is preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.

R ²³ is an aliphatic cyclic group having the structure (I) represented by the general formula (I-1).
In formula (I-1), the fluorinated alkyl group for R ²⁴ and R ²⁵ preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and most preferably 1 carbon atom.
The fluorinated alkyl group has a fluorination rate (ratio (%) of “number of fluorine atoms” to “total number of fluorine atoms and number of hydrogen atoms” in the fluorinated alkyl group) of 50 to 100. % Is preferable, 70 to 100% is more preferable, and 100% is particularly preferable.
R ²⁴ and R ²⁵ are preferably a fluorinated alkyl group, and particularly preferably a trifluoromethyl group.

X ²¹ and X ²² are each a carbon atom constituting the ring skeleton of the aliphatic cyclic group having the structure (I).
That is, part or all of the ring skeleton of the aliphatic cyclic group for R ²³ is constituted by X ²¹ —O—C—X ²² in the structure (I).
The aliphatic cyclic group for R ²³ may be a monocyclic group, may be a polycyclic group, and is preferably a polycyclic group.
Here, the monocyclic group in the aliphatic cyclic group of R ²³ is one aliphatic group in which part or all of the ring skeleton is constituted by X ²¹ —O—C—X ²² in the structure (I). A group obtained by removing one or more hydrogen atoms from a ring (hereinafter sometimes referred to as a specific ring). The polycyclic group is a group obtained by removing one or more hydrogen atoms from a condensed ring composed of the specific ring and an aliphatic ring sharing two or more carbon atoms with the specific ring.
The specific ring may be a ring (4-membered ring) in which the entire ring skeleton is constituted by X ²¹ —O—C—X ²² in structure (I), or X ²¹ — in structure (I). A ring (a ring having 5 or more members) in which a part of the ring skeleton is constituted by O—C—X ²² may be used.
Examples of the ring having 5 or more members include four consecutive carbon atoms (C—C—C—C—C) among the carbon atoms constituting the ring skeleton of a monocycloalkane having 5 or more carbon atoms such as cyclopentane and cyclohexane. ) Is substituted with X ²¹ —O—C—X ²² in the structure (I).
The specific ring is preferably a 4-6 membered ring.

In the case where the aliphatic cyclic group for R ²³ is a polycyclic group, the aliphatic ring constituting the condensed ring together with the specific ring may be monocyclic or polycyclic. Further, the aliphatic ring may be saturated, unsaturated, or saturated. Specific examples of the saturated aliphatic ring include, for example, monocycloalkanes such as cyclopentane and cyclohexane; polycycloalkanes such as norbornane, isobornane, adamantane, tricyclodecane, and tetracyclododecane. Among these, cyclohexane and / or norbornane are preferable, and norbornane is particularly preferable.

The aliphatic cyclic group for R ²³ may have a substituent. Here, “having a substituent” means that a hydrogen atom bonded to the ring skeleton of the aliphatic cyclic group is substituted with a substituent. Examples of the substituent include a lower alkyl group.

When the aliphatic cyclic group of R ²³ is a polycyclic group, the atom adjacent to R ²³ (when a is 0, it is an oxygen atom, and when a is an integer of 1 to 3, it is a carbon atom. Is preferably bonded to the carbon atom constituting the aliphatic ring constituting the condensed ring together with the specific ring, not the specific ring.

In the present invention, R ²³ is preferably a group represented by the following general formula (II-1).

［式（ＩＩ−１）中、Ｒ^２４およびＲ^２５はそれぞれ独立してフッ素原子またはフッ素化アルキル基であり、Ｒ^２６は炭素数１〜５のアルキレン基であり、ｂは０〜２の整数であり、ｃは０〜２の整数であり、かつｂ＋ｃは０〜２の整数であり、ｄは０または１である。］

[In Formula (II-1), R ²⁴ and R ²⁵ each independently represent a fluorine atom or a fluorinated alkyl group, R ²⁶ represents an alkylene group having 1 to 5 carbon atoms, and b represents an integer of 0 to 2. And c is an integer of 0 to 2, and b + c is an integer of 0 to 2, and d is 0 or 1. ]

Wherein ^{(II-1), R 24} and ^{R 25} are the same as ^{R 24} and ^{R 25} in the formula (I-1).
R ²⁶ is an alkylene group having 1 to 5 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms. For example, methylene group, ethylene group, n-propylene group, isopropylene group (—C (CH ₃ ) ₂ —) Linear or branched alkylene groups such as Among these, a methylene group is particularly preferable.
b and c are each independently an integer of 0 to 2, and it is sufficient that b + c is an integer of 0 to 2. Most preferably, b = 0 and c = 0, that is, b + c = 0.
d is 0 or 1, and is preferably 1.

The group represented by the general formula (II-1) may have a substituent on the ring skeleton. Examples of the substituent include the same as those mentioned as the substituent that the aliphatic cyclic group for R ²³ may have.

  In the present invention, the structural unit (c1) is preferably a group represented by the following general formula (c1-1-1) or (c1-1-2), and particularly represented by the formula (c1-1-1). Preferred are the groups

In formula (c1-1-1) and formula (c1-1-2), R ²⁷ and R ²⁸ each independently represent a fluorine atom or a fluorinated lower alkyl group, and are the same as R ²⁴ and R ²⁵ described above. Can be mentioned. Most preferably, each of R ²⁷ and R ²⁸ is a trifluoromethyl group.
R ²⁹ is an alkyl group having 1 to 5 carbon atoms. If R ²⁹ there are a plurality, the plurality of R ²⁹ may be each the same or different.
f is an integer of 0 to 2, preferably 0 to 1, and most preferably 0.

  In the component (C), the proportion of the structural unit (c1) is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, based on all the structural units constituting the component (C). It may be mol%. The effect of this invention improves that the ratio of a structural unit (c1) is 50 mol% or more.

The component (C) may contain other structural units (hereinafter referred to as structural unit (c2)) other than the structural unit (c1) as long as the effects of the present invention are not impaired.
As the structural unit (c2), any monomer may be used as long as the monomer that derives the structural unit can be copolymerized with the monomer that derives the structural unit (c1). Specifically, for example, the structural units (a1) to (a4) mentioned above for the component (A1) can be mentioned.

The component (C) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
In addition, the component (C) is used in combination with a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH at the time of the above-described polymerization. A —C (CF ₃ ) ₂ —OH group may be introduced into the group. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw) of the component (C) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and most preferably 5000 to 20000. preferable. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and when it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
The dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and still more preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

As the component (C), any one type may be used alone, or two or more types may be used in combination.
The content of the component (C) in the resist composition for immersion exposure according to the present invention is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (A). 5 parts by mass is more preferable. When it is at least the lower limit of the above range, the effect of improving the hydrophobicity of the resist composition is excellent, and when it is at most the upper limit, the lithography properties are improved.

<Optional component>
The resist composition for immersion exposure according to the present invention preferably further contains a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component. As a result, the resist pattern shape, the stability over time and the like are improved.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, and the like; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are more preferable. Among the alkyl alcohol amines, alkyl alcohol amines having an alkyl group with an alkyl group having 2 to 5 carbon atoms are preferred, and triethanolamine and / or triisopropanolamine are most preferred.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
As the component (D), any one type may be used alone, or two or more types may be used in combination.
When the component (D) is contained in the resist composition, the component (D) is usually used in the range of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A).

In the resist composition for immersion exposure according to the present invention, an organic carboxylic acid, a phosphorus oxoacid, and a phosphorus oxoacid can be used as optional components for the purpose of preventing sensitivity deterioration and improving the resist pattern shape, stability over time, etc. At least one compound (E) selected from the group consisting of derivatives thereof (hereinafter referred to as component (E)) can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of the phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
(E) A component may be used individually by 1 type and may use 2 or more types together.
When the component (E) is contained in the resist composition, the component (E) is usually used at a ratio of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

  The resist composition for immersion exposure according to the present invention further contains miscible additives, for example, an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, a dissolution agent, if desired. An inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

The resist composition for immersion exposure according to the present invention can be produced by dissolving a material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any one of conventionally known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol and derivatives thereof;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether;
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate;
Examples include aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene. be able to.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Of these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of component (S) used is not particularly limited, but it is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. -20% by mass, preferably 5-15% by mass.

  The material can be dissolved in the component (S), for example, by simply mixing and stirring the above components by a usual method. If necessary, a disperser such as a dissolver, a homogenizer, or a three-roll mill is used. It may be dispersed and mixed. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

Since the resist composition for immersion exposure according to the present invention has good lithography characteristics, which are characteristics required for a resist composition used for immersion exposure, and hydrophobicity suitable for immersion exposure, It is suitably used for immersion exposure.
That is, as described above, the immersion exposure is performed by exposing the portion between the lens and the resist film on the wafer, which is conventionally filled with an inert gas such as air or nitrogen, at a time higher than the refractive index of air. This is a method including a step of performing exposure (immersion exposure) in a state filled with a solvent (immersion medium) having a large refractive index. In immersion exposure, when the resist film and the immersion solvent come into contact with each other, elution (substance elution) of substances ((B) component, (D) component, etc.) in the resist film into the immersion solvent occurs. Substance elution causes phenomena such as alteration of the resist layer and change in the refractive index of the immersion solvent, thereby deteriorating the lithography properties. The amount of this substance elution is affected by the characteristics of the resist film surface (for example, hydrophilicity / hydrophobicity). Therefore, for example, it is presumed that elution of the substance is reduced by increasing the hydrophobicity of the resist film surface.
Since the resist composition for immersion exposure of the present invention contains the component (C) having a specific structural unit (c1) containing a fluorine atom, the resist composition is compared with the case of not containing the component (C). The resist film formed using the composition has high hydrophobicity. Therefore, according to the positive resist composition of the present invention, substance elution during immersion exposure can be suppressed.
Moreover, the resist composition for immersion exposure according to the present invention also has various lithographic properties as shown in Examples described later. For example, by using the resist composition for immersion exposure according to the present invention, a fine resist pattern having a line width of a line and space (L / S) pattern of 120 nm or less can be formed. In addition, since the component (C) has an aliphatic cyclic group, it has excellent etching resistance, and the etching resistance is particularly high in the aliphatic cyclic group in R ²³ in the formula (I-1). It is particularly good when it is a cyclic group.

The resist film formed using the resist composition for immersion exposure according to the present invention contains the component (C), so that the hydrophobicity of the resist film is increased as compared with the case where the component (C) is not contained. , Contact angle to water, for example, static contact angle (angle between the surface of the water droplet on the resist film in the horizontal state and the resist film surface), dynamic contact angle (water droplets fall when the resist film is tilted) Contact angle at the beginning: There are contact angle (advance angle) at the end point in the forward direction of the drop of water and contact angle (retreat angle) at the end point in the rear direction of the drop direction), fall angle (inclination of the resist film) The inclination angle of the resist film when the water droplet starts to fall down) changes. For example, the higher the hydrophobicity of the resist film, the larger the static contact angle and dynamic contact angle, while the smaller the falling angle.
Here, as shown in FIG. 1, when the plane 2 on which the droplet 1 is placed is gradually inclined, the advance angle starts to move (drop) on the plane 2 when the droplet 1 is gradually inclined. Is the angle θ ₁ formed by the surface of the droplet at the lower end 1 a of the droplet 1 and the plane 2. At this time (when the droplet 1 starts moving (falling) on the plane 2), the angle θ2 formed by the droplet surface at the upper end 1b of the droplet 1 and the plane ₂ is the receding angle, The inclination angle θ _{3 of the} plane 2 is the falling angle.
In this specification, the static contact angle, the dynamic contact angle, and the sliding angle are measured as follows.
First, a resist composition solution is spin-coated on a silicon substrate and then heated at 90 ° C. for 90 seconds to form a resist film.
Next, DROP MASTER-700 (manufactured by Kyowa Interface Science Co., Ltd.), AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.) It can measure using commercially available measuring apparatuses, such as.

In the resist composition for immersion exposure according to the present invention, the measured value of the receding angle in a resist film obtained using the resist composition is preferably 55 degrees or more, more preferably 55 to 150 degrees, It is particularly preferably 55 to 130 degrees, and most preferably 60 to 100 degrees. When the receding angle is 55 degrees or more, the substance elution suppression effect during immersion exposure is improved. The reason for this is not clear, but one of the main factors may be related to the hydrophobicity of the resist film. In other words, since an aqueous medium such as water is used as the immersion medium, the immersion medium is quickly removed from the resist film surface when the immersion medium is removed after immersion exposure because of high hydrophobicity. It is presumed that the fact that it can be removed has an effect. Further, when the receding angle is 150 degrees or less, the lithography characteristics and the like are good.
For the same reason, in the resist composition for immersion exposure according to the present invention, the measured value of the advance angle in the resist film obtained using the resist composition is preferably 80 degrees or more, and is 85 to 100 degrees. Is more preferable, and it is especially preferable that it is 85-95 degree | times.
For the same reason, the resist composition for immersion exposure according to the present invention preferably has a measured value of a static contact angle in a resist film obtained by using the resist composition of 70 degrees or more, and 75 to 95 degrees. It is more preferable that it is 80 to 90 degrees.
Further, in the resist composition for immersion exposure according to the present invention, the measured value of the falling angle in the resist film obtained using the resist composition is preferably 36 degrees or less, more preferably 10 to 36 degrees. It is preferably 12 to 30 degrees, and most preferably 15 to 25 degrees. When the sliding angle is 36 ° or less, the substance elution suppression effect during immersion exposure is improved. In addition, when the falling angle is 10 degrees or more, the lithography characteristics and the like are good.

  The above-mentioned various angles (static contact angle, dynamic contact angle (advance angle, receding angle), sliding angle, etc.) are determined depending on the composition of the resist composition for immersion exposure, for example, the blending amount of component (C) It can be adjusted by adjusting the proportion of the structural unit (c1), the type of the component (A), and the like. For example, the higher the structural unit (c1) in the component (C) and the higher the content of the component (C), the higher the hydrophobicity of the resulting resist composition. Increases and the sliding angle decreases.

Further, in the present invention, as described above, substance elution from the resist film during immersion exposure to the immersion solvent is suppressed. Therefore, in immersion exposure, by using the resist composition for immersion exposure according to the present invention, it is possible to suppress alteration of the resist film and change in the refractive index of the immersion solvent. Therefore, the shape of the resist pattern to be formed is improved, for example, by suppressing fluctuations in the refractive index of the immersion solvent.
Further, the contamination of the lens of the exposure apparatus can be reduced, so that it is not necessary to take a protective measure against these, and the process and the exposure apparatus can be simplified.
Further, as described above, when performing immersion exposure using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium moves following the movement of the lens. Although followability is required, in the present invention, the resist film has high hydrophobicity and high water followability. In addition, the resist composition for immersion exposure according to the present invention has good lithography characteristics, and can be used to form a resist pattern without any practical problems when used as a resist in immersion exposure.
Thus, the resist composition for immersion exposure according to the present invention has good lithography properties (sensitivity, resolution, etching resistance, etc.), hydrophobicity, substance elution suppression ability, water followability, etc.) In addition, it has sufficient characteristics required for a resist material in immersion exposure.

≪Resist pattern formation method≫
Next, the resist pattern forming method of the present invention will be described.
The resist pattern forming method of the present invention includes a step of forming a resist film on a support using the resist composition for immersion exposure of the present invention, a step of immersing the resist film, and developing the resist film. And a step of forming a resist pattern.

A preferred example of the method for forming a resist pattern of the present invention is shown below.
First, after applying the resist composition for immersion exposure of the present invention on a support with a spinner or the like, a resist film is formed by performing pre-baking (post-apply baking (PAB) treatment).
The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
In addition, the support may be a substrate in which an inorganic and / or organic film is provided on the above-described substrate. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include organic films such as an organic antireflection film (organic BARC) and a lower organic film in a multilayer resist method.
Here, the multilayer resist method is a method in which at least one organic film (lower organic film) and at least one resist film (upper resist film) are provided on a substrate, and the resist pattern formed on the upper resist film is used as a mask. This is a method of patterning a lower organic film, and it is said that a pattern with a high aspect ratio can be formed. That is, according to the multilayer resist method, the required thickness can be secured by the lower organic film, so that the resist film can be thinned and a fine pattern with a high aspect ratio can be formed.
In the multilayer resist method, basically, a method having a two-layer structure of an upper layer resist film and a lower layer organic film (two layer resist method), and one or more intermediate layers between the upper layer resist film and the lower layer organic film And a method of forming a multilayer structure of three or more layers (metal thin film etc.) (three-layer resist method).

  After the resist film is formed, an organic antireflection film may be further provided on the resist film to form a three-layer laminate including a support, a resist film, and an antireflection film. The antireflection film provided on the resist film is preferably soluble in an alkali developer.

  The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the resist composition for immersion exposure to be used.

Next, liquid immersion lithography is selectively performed on the resist film obtained above through a desired mask pattern. At this time, the space between the resist film and the lens at the lowest position of the exposure apparatus is previously filled with a solvent (immersion medium) having a refractive index larger than that of air, and exposure (immersion exposure) is performed in this state.
The wavelength used for the exposure is not particularly limited, and can be performed using radiation such as an ArF excimer laser, a KrF excimer laser, or an F ₂ laser. The resist composition according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film formed using the resist composition for immersion exposure is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, a silicon-based solvent, and a hydrocarbon-based solvent.
Specific examples of the fluorine-based inert _liquid, mainly composed of _{C 3 HC l2 F 5, C} 4 F 9 OCH 3, C 4 F 9 OC 2 H 5, C 5 H 3 F 7 , etc. A fluorine- Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).
The resist composition for immersion exposure of the present invention is not particularly adversely affected by water and is excellent in sensitivity and resist pattern profile shape. Therefore, in the present invention, water is preferably used as the immersion medium. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

  Next, after the immersion exposure step is completed, post-exposure heating (post-exposure baking (PEB)) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. The water rinsing can be performed, for example, by dropping or spraying water on the substrate surface while rotating the substrate to wash away the developer on the substrate and the resist composition for immersion exposure dissolved by the developer. Then, drying is performed to obtain a resist pattern in which the resist film (the coating film of the resist composition for immersion exposure) is patterned into a shape corresponding to the mask pattern.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
Resin (A) -1 used as the component (A) in the following Examples 1 to 4 and Comparative Example 1 is copolymerized using the following monomers (1) to (3) using a known drop polymerization method. I got it.

The obtained resin was subjected to GPC measurement, and the mass average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined. As a result, Mw of (A) -1 was 10,000, and Mw / Mn was 2.0.
The structure of (A) -1 is shown below. In the formula, the number attached to the lower right of () indicates the ratio (mol%) of each structural unit to the total of all structural units constituting the resin.

Moreover, in the following Examples 1-4, resin (C) -1 (Mw = 14300. Mw / Mn = 1.7.) Represented by the following formula (C) -1 is used as the (C) component. It was.
Resin (C) -1 uses a monomer represented by the following chemical formula (C) -0 (manufactured by Central Glass Co., Ltd.) and refers to JP-A-2005-232095 and JP-A-2005-316352. It is a synthesized homopolymer.

Examples 1-4, Comparative Example 1
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 1 has the following meaning, and the numerical value in [] is the blending amount (part by mass).
(B) -1: a compound represented by the following formula (B) -1.
(B) -2: A compound represented by the following formula (B) -2.
(D) -1: Triethanolamine.
(S) -1: PGMEA / PGME = 60/40 (mass ratio) mixed solvent.

The following evaluation was performed using the obtained resist composition.
<Hydrophobic evaluation>
The static contact angle, dynamic contact angle (advance angle and receding angle) and fall angle (hereinafter collectively referred to as contact angle etc.) of the resist film surface before and after exposure are measured by the following procedure. Thus, the hydrophobicity of the resist film was evaluated.
An organic antireflection film composition “ARC-29A” (trade name, manufactured by Brewer Science Co., Ltd.) is applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a thickness of 77 nm was formed. The resist compositions of Examples 1 to 5 and Comparative Example 1 were applied onto the antireflection film using a spinner, prebaked on a hot plate at 115 ° C. for 60 seconds, and dried. A resist film having a thickness of 150 nm was formed.
50 μL of water was dropped onto the surface of the resist film (resist film before exposure), and the contact angle and the like were measured using DROP MASTER-700 manufactured by Kyowa Interface Science Co., Ltd.

Further, a resist film is formed in the same manner as described above, and an ArF excimer laser (ArF exposure apparatus NSR-S-302 (manufactured by Nikon; NA (numerical aperture) = 0.60, σ = 0.75)) is used. 193 nm) was subjected to open frame exposure (exposure not through a mask) (exposure amount 20 mJ / cm ² ), and PEB treatment was further performed at 115 ° C. for 60 seconds. After PEB treatment, the contact angle on the surface of the resist film (resist film after exposure) was measured in the same manner as described above.

Tables 2 to 3 show measurement results such as the contact angle of the resist film before and after exposure. In Tables 2 to 3, the ratio of the amount of component (C) to the amount of component (A) in each resist composition (hereinafter simply referred to as “(C) component ratio”. Unit: mass%) ).
Further, from these results, a graph was created with the (C) component ratio (% by mass) on the horizontal axis and the angle (°) such as the contact angle on the vertical axis for each of before and after exposure. This graph is shown in FIG. 2 and FIG.
As shown in these results, in Examples 1 to 4 in which (A) -1 and (C) -1 were used in combination, compared with Comparative Example 1 in which (C) -1 was not blended, before exposure.・ The static contact angle and dynamic contact angle increased and the falling angle decreased after exposure. Further, the difference in contact angle before and after exposure was small. From this result, it was confirmed that the resist film obtained using the resist compositions of Examples 1 to 4 was a film having higher hydrophobicity than the resist film obtained using the resist composition of Comparative Example 1. .

<Lithography characteristics evaluation>
"Resolution and sensitivity"
About the resist composition of Examples 1-2 and the comparative example 1, the resist pattern was formed in the following procedures, respectively.
A resist film is formed in the same procedure as shown in the hydrophobicity evaluation, and an ArF exposure apparatus NSR-S-302 (Nikon Corporation; NA (numerical aperture) = 0.60, 2 / ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by three-band illumination. Then, PEB processing was performed at 115 ° C. for 60 seconds, and further development processing was performed at 23 ° C. with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds.
As a result, a space-and-line resist pattern (hereinafter referred to as S / L pattern) having a space width of 120 nm and a line width of 120 nm (pitch 240 nm) was formed in any of the resist compositions.
At this time, the optimum exposure amount (Eop) (unit: mJ / cm ² (energy amount per unit area)), that is, the sensitivity at which an S / L pattern having a space width of 120 nm and a pitch of 240 nm is formed was obtained. As a result, the sensitivity of Examples 1-2 and Comparative Example 1 was 18.0 mJ / cm ² , which was the same.

"LWR (Line Wise Roughness)"
In each S / L pattern formed by the Eop, a side length SEM (scanning electron microscope, acceleration voltage 800 V, trade name: S-9220, manufactured by Hitachi, Ltd.) is used to change the line width in the longitudinal direction of the line. Five locations were measured, and from the result, a triple value (3 s) of the standard deviation (s) was calculated as a scale indicating LWR. As a result, in any example using any resist composition, the value of 3s was 10 nm, which was equivalent. Note that the smaller the value of 3s, the smaller the roughness of the line width, which means that a more uniform S / L pattern was obtained.

“MEF (Mask Error Factor)”
In the above Eop, an S / L pattern is formed using a mask pattern targeting an S / L pattern with a line width of 120 nm and a pitch of 260 nm and a mask pattern targeting an S / L pattern with a line width of 130 nm and a pitch of 260 nm. The MEF value was obtained from the following equation.
MEF = | CD ₁₃₀ −CD ₁₂₀ | / | MD ₁₃₀ −MD ₁₂₀ |
In the above formula, CD ₁₃₀ and CD ₁₂₀ are the actual line widths (nm) of the S / L pattern formed using the mask pattern targeting a line width of 120 nm and a line width of 130 nm, respectively. MD ₁₃₀ and MD ₁₂₀ are line widths (nm) targeted by the mask pattern, respectively, and MD ₁₃₀ = 130 and MD ₁₂₀ = 120. MEF is a parameter indicating how faithfully mask patterns with different line widths and apertures can be reproduced with the same exposure when the pitch is fixed (mask reproducibility). The closer it is, the better the mask reproducibility is.
As a result, the MEF was almost the same in any of the resist compositions.

"EL margin"
An S / L pattern was formed in the same manner as above except that the exposure amount was changed, and the obtained S / L pattern was observed with a SEM (scanning electron microscope). In each S / L pattern, the space width was The exposure amount that can be formed within the target dimension (120 nm) ± 5% (that is, within the range of 114 to 126 nm) was determined, and the percentage of the Eop determined above was calculated. The larger the value, the smaller the dimensional change amount of the pattern formed with respect to the change amount of the exposure amount, and the better the EL margin. Note that the EL margin provides a resist pattern faithful to the mask, that is, an exposure amount range in which a resist pattern can be formed with a dimension within which the deviation from the target dimension is within a predetermined range when the exposure is changed. It is the range of exposure amount.
As a result, the EL margins of Examples 1 and 2 and Comparative Example 1 were almost equal.

As shown in the above results, the resist compositions of Examples 1 and 2 had good performance at the same level as the resist composition of Comparative Example 1 with respect to various lithography characteristics.
From these results, the resist compositions of Examples 1 to 4 containing the component (A), the component (B) and the component (C) can form a highly hydrophobic resist film and have good lithography characteristics. I was able to confirm.

It is a figure explaining advancing angle ((theta) ₁ ), receding angle ((theta) ₂ ), and falling angle ((theta) ₃ ). In an Example, it is a graph which shows the relationship between (C) component ratio (mass%), the contact angle of the resist film before exposure, etc. In an Example, it is a graph which shows the relationship between (C) component ratio (mass%), the contact angle of the resist film after exposure, etc.

Claims (9)

A base component (A) that has alkali solubility changed by the action of an acid and does not have the structural unit (c1) represented by the following general formula (c1-1), and an acid generator that generates an acid upon exposure. A resist composition for immersion exposure comprising a component (B) and a fluororesin component (C) having the structural unit (c1).

[In the formula (c1-1), R is a hydrogen atom, a lower alkyl group, a halogen atom or a halogenated lower alkyl group, R ²¹ and R ²² are each independently a hydrogen atom or a lower alkyl group, and a is R is an integer of 0 to 3, and R ²³ is an aliphatic cyclic group having the structure (I) represented by the following general formula (I-1). ]

[In Formula (I-1), R ²⁴ and R ²⁵ each independently represent a fluorine atom or a fluorinated alkyl group, and X ²¹ and X ²² each represent a ring of an aliphatic cyclic group having the structure (I). It is a carbon atom constituting the skeleton. ] The resist composition for immersion exposure according to claim 1, wherein R ²³ in the formula (c1-1) is a group represented by the following general formula (II-1).

[In Formula (II-1), R ²⁴ and R ²⁵ each independently represent a fluorine atom or a fluorinated alkyl group, R ²⁶ represents an alkylene group having 1 to 5 carbon atoms, and b represents an integer of 0 to 2. And c is an integer of 0 to 2, and b + c is an integer of 0 to 2, and d is 0 or 1. ]   The resist composition for immersion exposure according to claim 1 or 2, wherein the content of the fluororesin component (C) is in the range of 0.1 to 10% by mass with respect to the substrate component (A).   The liquid immersion according to any one of claims 1 to 3, wherein the base material component (A) is a resin (A1) having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid. Resist composition for exposure.   The resist composition for immersion exposure according to claim 4, wherein the resin (A1) has a structural unit (a1) derived from an acrylate ester having an acid dissociable, dissolution inhibiting group.   The resist composition for immersion exposure according to claim 5, wherein the resin (A1) further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.   The resist composition for immersion exposure according to claim 5 or 6, wherein the resin (A1) further comprises a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.   Furthermore, the resist composition for immersion exposure as described in any one of Claims 1-7 containing a nitrogen-containing organic compound (D). A step of forming a resist film on a support using the resist composition for immersion exposure according to any one of claims 1 to 8, a step of immersing the resist film, and developing the resist film A resist pattern forming method including a step of forming a resist pattern.

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